I dunno. I take it but supplemental Zinc seems to have little effect for me (in general). Maybe because my Doc says my zinc levels are great. Not getting too run down (ha!) and high exposures(!) seem to be about 100x factors for me (colds, mainly; I usually get flu vaccs and can’t remember when I’ve had flu myself, unless it was pretty mild.)
In general I’d think that if most cells absorbed Zinc, but poorly for some reason, viral replication would not be slowed much. Kinda like weak 2,4-D on resistant dandelions.
Weirdly, my last blood tests showed slight anemia possibly due to poor iron absorption. More tests due - maybe I’m eating too much bran cereal with milk, and, I do consume lots of milk anyway. Maybe too much.
On the 2nd point, my diet is pretty high in NAC. I might ask my doc if my last round of blood tests showed any evidence I’m not producing good levels of Glutathione, but I have no reason to suspect not.
One of many studies on NAC, this one wrt COVID:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7649937/
-PJ